A packaged electronic system is formed of a base having a surface and a plurality of discrete electronic components disposed on the base surface. An absorbing cover reduces the electromagnetic resonance produced by the discrete electronic components disposed within the packaged system. The entire cover is molded using a composite electromagnetic wave-absorbing plastic material. The cover is selectively plated to satisfy the shielding requirements of the packaged system.
|
6. A packaged electronic system, comprising:
a base having a surface; a plurality of discrete electronic components disposed on said surface; a cover disposed on said base surface and having a molded body, an exterior surface, and an interior surface, wherein said molded body being formed of a material exhibiting electromagnetic wave-absorbing characteristics; and wherein said cover interior surface has an electrically conducting material selectively deposited thereon. 1. A packaged electronic system, comprising:
a base having a surface; a plurality of discrete electronic components disposed on said surface; a cover disposed on said base surface and having a molded body, an exterior surface, and an interior surface, wherein said molded body being formed of a material exhibiting electromagnetic wave-absorbing characteristics; and wherein said molded body comprises a plurality of channels, a plurality of cavities, and a plurality of walls on said interior surface. 2. A packaged electronic system as recited in
3. A packaged electronic system as recited in
4. A packaged electronic system as recited in
5. A packaged electronic system as recited in
7. A packaged electronic system as recited in
|
1. Field of the Invention
The present invention relates generally to packaged electronic systems and, more specifically to such a system that includes an absorbing cover which reduces the electromagnetic resonance produced by the circuitry of the packaged microwave components.
2. Description of the Prior Art
The circuitry contained in packaged electronic systems is a source of electromagnetic resonance that may adversely affect the performance of the active circuitry contained therein by generating electromagnetic interference (EMI) or radio frequency interference (RFI).
Traditional microwave packages are metal, with a cover grounded to a housing or base. The package covers typically comprise many channels and cavities and, by attaching the package cover to the package base, the closed cavities or channels of the cover provide structural isolation of the electronic fields produced by a particular circuit housed within the package. It is generally known that there can be electromagnetic resonance within these cavities and channels, especially if the circuits are operating at very high frequencies. A number of techniques are described in the prior art that attempt to reduce the resonance effect on the circuitry contained within a microwave package.
As illustrated in
The technique disclosed in U.S. Pat. No. 5,397,854 attempts to minimize the complexity of the fabrication steps required by the method disclosed above. The '854 patent describes using an ink which contains a combination of a resin and a microwave absorbing material, such as iron or ferrite and screen printing or mask printing the ink onto the ceilings of the cavities and channels of the package cover. Although the '854 patent eliminates having to manually align and adhere the sheets of absorber in the cavities and channels of the cover, the method disclosed in the '854 patent introduces a different set of complexities. For example, a mask or a screen is required where the pattern of the mask or screen must precisely match the pattern of cavities and channels of the cover, the mask or screen must be accurately aligned with the cover prior to the printing process and following the printing process the ink must be hardened through a curing or drying process.
As previously discussed, present packaged electronic systems use a variety of techniques to reduce the electromagnetic interference caused by the emissions of active circuitry. However, these techniques require complicated fabrication processes, and are not cost effective. The greater the complexity, the more assembly costs are increased and reliability decreased.
Based on techniques known in the art for packaged microwave systems, a method for reducing electromagnetic interference of packaged microwave systems while reducing the cost of manufacturing electromagnetic wave absorbing covers is highly desirable.
It is an aspect of the present invention to provide a packaged electronic system that includes a base having a surface and a plurality of discrete electronic components disposed on the base surface. The present invention also includes a cover disposed on the base surface, wherein the cover has a molded body, an exterior surface, and an interior surface. The cover body may be selectively plated and is formed of a material having electromagnetic wave-absorbing characteristics.
Reference is now made to the following specification and attached drawings, wherein:
The present invention discloses a packaged microwave system that reduces the interference from electromagnetic emissions within the package and minimizes the manufacturing complexity and cost of the packaged system. Specifically, the present invention discloses a packaged microwave system where a cover is injection molded using a microwave absorbing thermoplastic material. The ability to injection mold the cover using microwave absorbing thermoplastic material has several advantages. First, the molding process eliminates the complex machining steps required for conventional metal covers. Second, injection molding, rather than machining, offers more flexibility in the design of various parts, and also reduces piece part prices. Further, by providing microwave-absorbing characteristics within the molded body of the RF cover the step of manually installing microwave-absorbing materials is eliminated. Finally, special adhesives are not needed to secure the microwave absorbing materials. Therefore, those of ordinary skill in the art should understand that the principles of the present invention are applicable to many types of packaged electronic systems.
Traditionally, packages are built in two pieces--a cover, and a flat base or housing. Referring to
Referring to
Referring to
Referring to
The covers (16, 19) of the previously described microwave packages (11, 40) are essential components of their respective packages. The covers (16, 19) provide isolation of electronic fields and signals contained within the packages (11, 40) and they also provide the microwave absorbing characteristics required for dampening any cavity (24, 23) electromagnetic resonance. For the purposes of the preferred embodiment, each cover body (18, 21) is a composite material 20 that includes a plastic material and an electromagnetic wave-absorbing material. The plastic material is chosen from the group of thermoplastics. Thermoplastics are preferred because they can be reflowed many times so scraps remaining after the molding process are reusable, and thermoplastics are injection moldable for fast cycle times and lower cost. Because plastics typically exhibit characteristics of coefficient of thermal expansion (CTE) and volume resistivity which are higher than their metal counterparts, it is important that a plastic is chosen which can accommodate loading (fillers) to meet the requirements of a particular packaged system. For example, the CTE value of thermoplastics can be lowered by adding fillers such as glass and carbon fibers and the volume resistivity can be lowered by adding conductive fillers such as stainless steel, nickel coated graphite, and polyacrylonitrile carbon fibers. Lowering the CTE and volume resistivity of the plastic cover allows the cover to have characteristics similar to the metal covers used in conventional microwave packages and have the RF absorbing properties that conventional metal covers do not have. The preferred thermoplastic material of the illustrated embodiment is 25% carbon fiber reinforced polyetherimide (PEI), however, it may also include 40% glass reinforced polyphenylenesulfide (PPS), acrylonitrile butadiene styrene (ABS), 9% carbon reinforced polyethylene terephthalate (PET), nylon, stainless steel filled carbon reinforced polyethersulfene (PES), or carbon filled stainless filled nylon.
The composite material 20 used to form the microwave package covers (16, 19) is further comprised of an electrically conductive and electromagnetic wave-absorbing material. The electromagnetic wave-absorbing material is chosen for its "lossy" effects and ability to absorb electromagnetic waves that may resonate and cause undesirable interference within an electronic package. The preferred electromagnetic wave absorbing material is ferrite, and is chosen for its high absorption threshold. Alternatively, the absorbing material may include stainless steel filled polycarbonate, stainless steel filled polyethersulfone, carbon fiber filled polycarbonate, ferrite filled liquid crystal polymer, or carbonyl iron filled liquid crystal polymer.
The exterior surfaces (32, 33) of the covers (16, 19) may be plated, as previously described, using a metal plating 30. The metal plating 30 is comprised of 40 μin electroless copper and 20 μin electroless nickel. Other plating materials may include copper, gold, conductive paints such as silver or similar materials suitable for plating.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described above.
Ferris, Matthew D., Allen, Barry R., Duprey, Randy J.
Patent | Priority | Assignee | Title |
10756426, | Jun 14 2016 | HITACHI ASTEMO, LTD | Millimeter-wave band communication device |
6617686, | Feb 08 2002 | STANOWSKI, DAVID RICHARD | Semiconductor device and method of isolating circuit regions |
6672902, | Dec 12 2001 | Intel Corporation | Reducing electromagnetic interference (EMI) emissions |
6797401, | Jun 20 2002 | Lockheed-Martin Corporation; Lockheed Martin Corporation | Electromagnetic wave absorbing materials |
6847115, | Sep 06 2001 | Silicon Bandwidth Inc. | Packaged semiconductor device for radio frequency shielding |
6972366, | May 19 2003 | Multilayer structure for absorbing electromagnetic wave and manufacturing method thereof | |
7039361, | Feb 01 2002 | Ciena Corporation | System and method for reducing electromagnetic interference |
7297423, | Mar 03 2004 | Sony Corporation | Printed circuit board |
7310236, | Jul 30 2003 | Sony Corporation | Electronic device |
7436056, | Apr 17 2006 | Fujitsu Limited | Electronic component package |
7677462, | Feb 24 2006 | OPSEC SECURITY GROUP, INC | Method of reducing electro-static discharge (ESD) from conductors on insulators |
7808091, | Jul 20 2001 | Saes Getters S.p.A. | Wafer structure with discrete gettering material |
7869216, | Aug 25 2008 | Honeywell International Inc | Composite avionics chassis |
7928326, | Feb 27 2009 | Hewlett-Packard Development Company, L.P. | Thermoformed EMI shield |
8213120, | Sep 10 2007 | International Business Machines Corporation | Flexible cable comprising liquid crystal polymer |
8226002, | Jun 30 2009 | Fujitsu Frontech Limited | Magnetic card reader |
8324515, | Oct 16 2007 | Honeywell International Inc. | Housings for electronic components |
8488334, | Feb 11 2008 | AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LIMITED | Electromagnetic interference (EMI) absorbing assembly and method for use in an optical transceiver module |
9846459, | Mar 28 2013 | ENTIT SOFTWARE LLC | Shield for an electronic device |
Patent | Priority | Assignee | Title |
5371404, | Feb 04 1993 | Freescale Semiconductor, Inc | Thermally conductive integrated circuit package with radio frequency shielding |
6090728, | May 01 1998 | 3M Innovative Properties Company | EMI shielding enclosures |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Jun 06 2000 | ALLEN, BARRY R | TRW Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 010973 | /0152 | |
Jun 06 2000 | DUPREY, RANDY J | TRW Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 010973 | /0152 | |
Jun 06 2000 | FERRIS, MATTHEW D | TRW Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 010973 | /0152 | |
Jul 25 2000 | TRW Inc. | (assignment on the face of the patent) | / | |||
Jan 22 2003 | TRW, INC N K A NORTHROP GRUMMAN SPACE AND MISSION SYSTEMS CORPORATION, AN OHIO CORPORATION | Northrop Grumman Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 013751 | /0849 | |
Nov 25 2009 | NORTHROP GRUMMAN CORPORTION | NORTHROP GRUMMAN SPACE & MISSION SYSTEMS CORP | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 023699 | /0551 | |
Dec 10 2009 | NORTHROP GRUMMAN SPACE & MISSION SYSTEMS CORP | Northrop Grumman Systems Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 023915 | /0446 |
Date | Maintenance Fee Events |
Dec 27 2005 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
Apr 08 2008 | ASPN: Payor Number Assigned. |
Dec 21 2009 | M1552: Payment of Maintenance Fee, 8th Year, Large Entity. |
Dec 19 2013 | M1553: Payment of Maintenance Fee, 12th Year, Large Entity. |
Date | Maintenance Schedule |
Jun 25 2005 | 4 years fee payment window open |
Dec 25 2005 | 6 months grace period start (w surcharge) |
Jun 25 2006 | patent expiry (for year 4) |
Jun 25 2008 | 2 years to revive unintentionally abandoned end. (for year 4) |
Jun 25 2009 | 8 years fee payment window open |
Dec 25 2009 | 6 months grace period start (w surcharge) |
Jun 25 2010 | patent expiry (for year 8) |
Jun 25 2012 | 2 years to revive unintentionally abandoned end. (for year 8) |
Jun 25 2013 | 12 years fee payment window open |
Dec 25 2013 | 6 months grace period start (w surcharge) |
Jun 25 2014 | patent expiry (for year 12) |
Jun 25 2016 | 2 years to revive unintentionally abandoned end. (for year 12) |